package com.lqk.demo.pessimisticlock.reentrantLock;

import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 哲学家就餐问题 ReentrantLock 解决
 */
@Slf4j
public class PhilosopherToEat {
    public static AtomicInteger STATE = new AtomicInteger(0b00000);
    public static void main(String[] args) {
        Chopstick c1 = new Chopstick("1");
        Chopstick c2 = new Chopstick("2");
        Chopstick c3 = new Chopstick("3");
        Chopstick c4 = new Chopstick("4");
        Chopstick c5 = new Chopstick("5");
        new Philosopher("苏格拉底", c1, c2).start();
        new Philosopher("柏拉图", c2, c3).start();
        new Philosopher("亚里士多德", c3, c4).start();
        new Philosopher("赫拉克利特", c4, c5).start();
        new Philosopher("阿基米德", c5, c1).start();
    }
}


@Slf4j(topic = "c.Philosopher")
class Philosopher extends Thread {
    Chopstick left;
    Chopstick right;
    public Philosopher(String name, Chopstick left, Chopstick right) {
        super(name);
        this.left = left;
        this.right = right;
    }

    @Override
    public void run() {
        while (true){
            //　尝试获得左手筷子
           if (left.tryLock()){
               try{
                   // 尝试获得右手筷子
                   if (right.tryLock()){
                       try{
                           eat();
                       }finally {
                           right.unlock();
                       }
                   }
               }finally {
                   // 获取里面的锁失败了，放弃自己手中的筷子
                   left.unlock();
               }
           }
        }
    }

    private void eat() {
        log.debug("eating...{}+{}", left, right);
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

class Chopstick extends ReentrantLock {
    String name;

    public Chopstick(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "筷子{" + name + '}';
    }
}
